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From Bruce Atherton <br...@callenish.com>
Subject OT: More trivia about dates than you ever wanted to know
Date Wed, 25 Jun 2003 20:22:52 GMT
At 08:59 AM 6/24/2003 -0700, Steve Loughran wrote:
>Martin Gainty wrote:
>>Alright I'll ask the dumb question
>>What happened on Jan 1 1601???
>>-Martin
>
>Of most interest to clocks is that by that day, the start of the 
>seventeenth century, most of the western world had updated their calendars 
>to adopt the no-leap-centuries-except-on-millennium rule that kept the 
>wall time more in sync with astronomicial time. So if you ignore dates 
>before 1601 you dont have to worry so much about when different countries 
>skipped a fair few days to catch up.

I'm not sure why Microsoft chose 1601 as their epoch date, but I don't 
think that it was for  this reason. True, 1601 avoids Pope Gregory's purge 
of 10 days from 1582 which many countries adopted within a few years, but 
there are many other countries that took decades or centuries to do so, 
including the country where Microsoft is based. Here are the dates when 
various countries changed over, from the "ncal" unix program:

  AL Albania        1912-11-30      IT Italy          1582-10-04
  AT Austria        1583-10-05      JP Japan          1918-12-18
  AU Australia      1752-09-02      LI Lithuania      1918-02-01
  BE Belgium        1582-12-14      LN Latin          9999-05-31
  BG Bulgaria       1916-03-18      LU Luxembourg     1582-12-14
*CA Canada         1752-09-02      LV Latvia         1918-02-01
  CH Switzerland    1655-02-28      NL Netherlands    1582-12-14
  CN China          1911-12-18      NO Norway         1700-02-18
  CZ Czech Republic 1584-01-06      PL Poland         1582-10-04
  DE Germany        1700-02-18      PT Portugal       1582-10-04
  DK Denmark        1700-02-18      RO Romania        1919-03-31
  ES Spain          1582-10-04      RU Russia         1918-01-31
  FI Finland        1753-02-17      SI Slovenia       1919-03-04
  FR France         1582-12-09      SE Sweden         1753-02-17
  GB United Kingdom 1752-09-02      TR Turkey         1926-12-18
  GR Greece         1924-03-09      US United States  1752-09-02
  HU Hungary        1587-10-21      YU Yugoslavia     1919-03-04
  IS Iceland        1700-11-16

Note that only 11 of these 24 countries changed before 1600. You can view 
the truly weird months for your locale using the "cal" or "ncal" programs. 
Here is the command if you are in Britain or one of her former colonies:

     $ cal 09 1752

(if you are in some other locale, you may need to run "ncal -s GB 09 1752" 
to see the same thing).

I don't know about other countries, but in England the Calendar Reform Act 
caused much confusion as landlords expected to be paid a month's rent while 
tenants had 11 fewer days to earn the money for it. People marched in the 
streets crying, "Give us back our 11 days!" Then there was the loss of 
January, February, and most of March from 1752 in England, but that is 
another story (and one neither the cal nor ncal programs demonstrate, 
probably because of the UI difficulty in showing a year change in the 
middle of a month).

I suspect the reason Microsoft chose 1601 is because they had to choose 
some date, and 1601 captures 99.999% of the dates that are likely to be 
entered by all but specialist users. Perhaps not coincidentally, I chose 
the same epoch year once for a program I wrote. Maybe it is some kind of 
forced choice like, "Pick a number between 1 and 4."









[If you chose a number before reading this, in all likelihood you chose "3"]



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